textproduct: Quad Cities

KEY MESSAGES

- Active stretch of weather through midweek, as an approaching system brings rounds of rainfall. Heavy rainfall is expected, with the potential for areal flooding and rises along area rivers.

- Drier weather returns late this week and through the weekend, with cool and pleasant weather.

SHORT TERM /THROUGH TONIGHT/

Issued at 131 AM CDT Tue Sep 29 2026

Upper ridge starts to track easterly as the trof over the eastern CONUS breaks down and moves offshore through tonight. Upper level southwesterly flow will then set up over the region, with a long fetch reaching towards the Eastern Pacific. As such, surface high pressure will move east of the area today. With high pressure tracking east, llvl winds will increase out of the southwest as well, setting the stage for warm advection into the region. Thus, temperatures will remain in the 70s throughout the area today, with moisture also on the rise. Some in our south might approach 80 this afternoon, which is above seasonal norms. We expect to remain dry through today and the first half of tonight, as plenty of dry air remains. Although, the increase in moisture that we do see will be in the way of increasing cloud cover through today, especially overnight tonight. We can expect a mix of mid/high clouds and sun through the day today, with overcast skies taking over tonight. The LLJ will increase quite a bit after sunset this evening, with the jet core oriented off to our west early. After midnight, the LLJ will start to center over our area, resulting in widespread increases in PoPs, with most seeing 50-80% chances for showers and embedded storms by sunrise Wednesday.

Severe weather is not expected at this time. Since rainfall will largely be starting after midnight, the threat for flash flooding is low, with WPC indicating largely <0.50" of rain overnight. Short term guidance and ensemble suites generally favor ~0.50" with 30-50% probabilities for most and about 50-70% for areas along/north of a line from Cedar Rapids to Dubuque, IA. Pockets of higher amounts up to an inch will be possible, but will remain localized.

LONG TERM /WEDNESDAY THROUGH MONDAY/

Issued at 131 AM CDT Tue Sep 29 2026

Wednesday/Thursday...

This will be quite the dreary stretch of weather, as we will continue to see bouts of vorticity flowing into the region ahead of the potent wave over the southern Rockies. There will also be a baroclinic zone that sets up, which will act as a focus for heavier rainfall. Although, there is much uncertainty on where this will set up at this time. Over the last few forecast runs, this axis has trended south, closer to the Interstate 80 corridor. Although, some guidance still has this north. In either case, we will be saturated with continuous bouts of vorticity passing overhead, favoring widespread rainfall through much of this timeframe. Overall, this will generally be in the form of persistent light- moderate rain showers passing through, with heavier rainfall expected at times. While there will be some dry time between showers, we are expecting to remain damp and showery throughout much of this timeframe. PWATs will be unseasonably high, roughly sitting around 2.00". Thus, if we manage to get more convective activity, then we will have the chance to see heavier rainfall. Although, there remains some uncertainty on this.

WPC continues to favor much of the area seeing 1.50-3.00" of rain when all is said and done, with localized areas potentially seeing 3.00"+. Confidence on these higher totals is low at this time, with ensemble guidance still in disagreement on amounts and location of the heaviest rainfall axis. The Euro suite remains the most aggressive with rainfall, highlighting chances for 2.00"+ of rain by Friday AM around 70-90% roughly along the I-80 corridor. Although, the GFS and other ensemble suites are farther north with this axis and only favoring 2.00"+ with about 40-70% probabilities. Areas that see the heaviest rainfall will have a low-end flash flood threat, with WPC highlighting our area in a Slight Risk, level 2 of 4, for Excessive Rainfall. One thing that might limit the flash flood threat will be the duration of rainfall. We are not expecting this rainfall to fall over a three hour period. Rather, we expect these totals over a 24-48 hour period. Thus, the long duration should allow for more infiltration than a short duration heavy rainfall event. Some rises on area rivers may be possible though, especially areas that saw rises with the recent heavy rainfall, along with the potential for some areal flooding.

Friday and Beyond...

Late this week and into the weekend, zonal to northwest flow will set up over the region. Some guidance hints at a wave passing through Saturday into Sunday, but moisture will be limited. The drying trend continues from last forecast package, with NBM indicating dry conditions through the weekend. Thus, this wave may just come through with some passing clouds and a wind shift. Otherwise, a cooler and pleasant weekend is currently forecast for the area.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1214 PM CDT Tue Sep 29 2026

VFR conditions through 06z/30 as moisture from the next system slowly arrives and lowers CIGS. We cannot fully rule out some 20-40% coverage for SHRA 21z/29 through 06z/30 but the incoming moisture needs to overcome the initially dry air. After 06z/30 conditions will slowly deteriorate to MVFR/IFR across eastern Iowa as the first round of moisture arrives. Although not included in the 18z TAFs, an isolated rumble of thunder cannot be ruled out after 09z/30.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.